Instructions

1. Gather all ingredients.
2. Preheat the oven to 400 degrees F (200 degrees C). Grease a 9-by-13-inch baking dish. Spread hash browns over the bottom of the baking dish.
3. Heat olive oil in a large skillet over medium heat. Add chorizo and onion, using a flat wooden spoon to break up the meat into smaller pieces. Cook until browned, about 8 to 10 minutes. Set aside.
4. Whisk eggs, 2 cups Cheddar cheese, 1 cup sour cream, milk, salt, and pepper in a large bowl. Stir in chorizo mixture.
5. Pour egg mixture over hash browns in baking dish. Dollop remaining 1/2 cup sour cream over eggs, and sprinkle with remaining 1 cup cheese.
6. Bake for 35 to 45 minutes, until just set in the center. Sprinkle with green onions, avocado, and pickled jalapeños, if using. Cut into squares and serve immediately.